The rectum and anus are believed to develop from the dorsal portion of the hindgut or cloacal cavity when lateral ingrowth of the mesenchyme forms the urorectal
septum in the midline.
Embryologically, the condition is caused by a developmental disorder of the cloaca and the transverse septum (urorectal
septum), which separates the gastrointestinal system from the urogenital system.
Atresia ani is a congenital malformation of anorectum due to failure of urorectal
fold to divide the cloaca completely or failure of perforation of fetal anal membranes that divides rectus and anus during fetal development, this condition is inherited in an autosomal recessive manner, but no candidate genes have been found unlike pigs (Albarella et al., 2017).
Constellation of these findings suggested urorectal
The cloaca is divided into two parts by a mesenchymal septum called the urorectal
septum divides the cloaca into the rectum and anal canal dorsally, and the bladder and lower urogenital tracts ventrally.
The estimated incidence is around 1 in 15000 live births.1 It occurs as a result of failure of the descent of the urorectal
septum and the persistence of the cloacal membrane during the development of the tail end of embryo in sixth week of gestation.
(17) consideran en base a estudios histologicos que revelan escasa inflamacion con epitelio escamoso en la pared de la fistula, aunado a aparicion usual de las manifestaciones clinicas en la edad neonatal, mas la falta de procesos infecciosos locales; confirman la naturaleza esencialmente congenita del trayecto, lo cual se explicaria por una alteracion en la embriogenesis del tabique urorectal
, el cual en condiciones normales, divide la cloaca en una porcion urogenital ventral y una dorsal debajo de la linea pubococcigea en el embrion.
Rica and colleagues (6) stated that asymmetry in the closure of the urorectal
septum results in an urethraperineal fistula.
This tube is di- vided into rectum and bladder at around 5th weeks of gestation by a caudal proliferation of mesoderm the urorectal
Septation of this by the urorectal
septum and Rathke's folds gives rise to the urogenital sinus (UGS), the cranial part of which gives rise the bladder.
Normally, as a baby grows inside the womb, the bladder and the urinary system separate from the bowel and the gastrointestinal system to form two separate systems by formation a urorectal